[1378] Myelodysplastic Syndrome with Complex Cytogenetics Abnormalities and CD34+ Megakaryocytes

Seble S Chekol, Qing Chen, Nahid M Nanaji. University of Maryland Medical Center, Baltimore, MD

Background: CD34 is a glycosylated surface protein expressed on immature hematopoietic precursor cells, endothelial cells and dendritic cells. Immunohistochemical staining for CD34 is frequently used to assess the blast number in myelodysplastic syndromes (MDS). Normal mature megakaryocytes (megs) generally do not express CD34. However, CD34+ megs were observed in some MDS cases. The goal of this study is to evaluate CD34 expression on megs and its relationship to cytogenetic abnormalities in MDS.
Design: We reviewed 24 MDS bone marrow biopsies diagnosed between 1/09 to 7/11 at UMMC. Patient ages for the MDS group ranged from 44 to 83 (mean 63) and for the control group ranged from 35 to 82, (mean 60). Each case was evaluated for the percentage of CD34+ megs and CD34+ myeloblasts, the morphology of megs and the cytogenetic findings. CD34+ in 10% or more of the megs was considered significant. thirty-nine non-MDS bone marrow biopsies were evaluated as controls; including marrows for tumor staging and from patients with myeloproliferative neoplasms during the same period of time at UMMC.
Results: 7/24 (29%) MDS bone marrow biopsies showed >10% CD34+ megs, whereas in the control group only 2/39 (5%) showed >10% CD34+ megs. Expression of CD34 was mostly seen in dysplastic megs. 4/7 MDS cases (57%) showed >50% CD34+ megs and three had complex cytogenetic abnormalities with all containing del[5] and one had del[20]. The remaining 3 out of 7 MDS cases (43%) had 10-20% CD34+ megs with normal Karyotype. MDS cases without significant CD34+ expression on megs showed complex cytogenetics abnormalities in 1/17 (6%) with del[5]. 5/7 (71%) MDS cases with significant CD34+ megs showed >5% myeloblasts whereas 3/17 cases (18%) without significant CD34+ megs showed >5% myeloblasts.

CasesNon-complex cytgentics abnComplex cytogentics abn (*= # of del[5])Normal cytogenetics# cases
MDS <10% CD34+ megs51 (*1)1117
MDS >10%-<50% CD34+ megs00 (*0)33
MDS >50% CD34+ megs13 (*3)04
Control <10% CD34+ megs25 (*0)3037
Control >10% CD34+ megs01 (*0)12

Conclusions: In this small study, CD34 expression on megs strongly indicates the presence of MDS and it is associated with complex cytogenetic abnormalities and increased myeloblasts. Del[5] is frequently seen among those MDS cases with high numbers of CD34+ megs. Therefore, assessment of CD34 expression on megs may represent a useful means in MDS bone marrow biopsy evaluation. Future studies with larger number of cases are needed to substantiate our current findings and to provide critical information regarding the prognostic significance of CD34+ megs in MDS.
Category: Hematopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 231, Tuesday Morning


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